This disclosure relates to a device and method for performing a handover test on a counterweight of an elevator system.
It is a requirement of the elevator safety code EN81-20 to perform a handover test on an elevator counterweight. A handover test is to be carried out once an elevator system has been assembled on site by an elevator field mechanic, in order to check it is operating correctly, before the elevator system is then handed over to the customer. The test is then often repeated at regular intervals, for example once a year, by a maintenance person.
In carrying out the handover test, it is required to test that the safety brakes (or safeties) of the counterweight correctly engage the counterweight guide rails. It is known in the art to test this by suspending the elevator car at the top of the hoistway e.g. by hanging the elevator car from a hook at the top of the hoistway e.g. from a hook used during lift installation, so that the counterweight is at the bottom of the hoistway above the pit. A jack is then placed in the pit and remotely controlled to lift the counterweight, causing the rope suspending the counterweight to go slack. The slack in the rope should cause the safeties of the counterweight to engage. In this position the maintenance person can then re-enter the pit and use a ladder to access the counterweight safeties and check that the safeties have engaged correctly, and if they have the test is considered to have been passed.
It would be desirable to provide an improvement in which this handover test could be carried out in a simpler and safer manner, and without requirement for a jack and a ladder. Providing a system in which the handover test can be carried out without a jack or ladder would also represent a cost reduction, since the safety code currently requires a supplier to supply these items with a unit, in order to facilitate the handover test.
According to a first aspect of this disclosure there is provided an elevator counterweight assembly, comprising:
According to a second aspect of this disclosure there is provided a method of carrying out a handover test for an elevator counterweight assembly, the method comprising:
It will be appreciated that, according to the present disclosure, a mechanical actuator is provided which enables a maintenance person to move the safety actuation mechanism of a counterweight between a normal position and a safety position, by actuating the mechanical actuator, and which therefore provides a simple and easy method of directly testing that the safety actuation mechanism is functioning correctly.
The safety actuation mechanism comprises the connection (e.g. sheave or hitch) for a suspension member. Thus, in use, under normal circumstances, the connection is lifted due to tension in the suspension member, and therefore the safety actuation mechanism is in the normal position (i.e. lifted upwards relative to the counterweight structure). During operation of the elevator system, if the suspension member suddenly goes slack and loses tension, the connection will no longer be lifted by tension in the suspension member, and the connection (and therefore the safety actuation mechanism) will drop under gravity, and optionally also due to a force provided by one or more biasing springs, to the safety position, in which (if everything is functioning correctly) the safety brakes will be deployed. The mechanical actuator according to the present disclosure allows the result of a slack suspension member (i.e. the movement of the safety actuation mechanism to the safety position) to be recreated (i.e. simulated), and therefore allows a maintenance person to test that the safety actuation mechanism functions correctly to deploy the at least one safety brake.
According to the present disclosure the safety actuation mechanism is configured to move relative to the counterweight structure, between a normal position, and a safety position. It will be understood by the skilled person that it is therefore only required that one of these components moves relative to the other, it is not important which of these components "actually" moves e.g. moves with respect to the frame of reference of the hoistway. For example, it may be that in a fault scenario which occurs during normal operation of the elevator system, the connection (e.g. counterweight sheave), and thus the safety actuation mechanism, moves downwards in the hoistway (faster than the counterweight structure), thus creating relative movement such that the safety actuation mechanism moves between the normal position and the safety position. It may be, however, that when the mechanical actuator is used to move the safety actuation mechanism from the normal position to the safety position, it is the counterweight structure which moves upwards (relative to the hoistway frame of reference) and the connection (e.g. counterweight sheave) is held in position by tension in the suspension member so the safety actuation mechanism remains stationary.
It will furthermore be understood by the skilled person that the mechanical actuator is arranged to apply a force to the safety actuation mechanism, and thus that it is the mechanical actuator itself which applies the force, which is the same force which moves the safety actuation mechanism i.e. it is a direct mechanical force. This is in contrast to the situation where a jack or other mechanical actuator is used to apply a first force (e.g. lifting the counterweight structure), which then allows a second force (e.g. gravity and/or spring force) to move the safety actuation mechanism from the normal position to the safety position.
In some examples, the mechanical actuator is arranged to move between a retracted position and an extended position, wherein, in the extended position, the mechanical actuator applies a force to the safety actuation mechanism. In some examples, the mechanical actuator maintains its position relative to the counterweight structure unless actuated to move relative to the counterweight structure and thereby apply a force to the safety actuation mechanism. In some examples, the motion of the safety actuation mechanism is reversible.
In some examples, the mechanical actuator may comprise a ratchet. In some examples, the mechanical actuator may comprise a piston. In some examples, the mechanical actuator may comprise a gas spring or mechanical spring that is manually released to apply a force to the safety actuation mechanism. In some examples, the mechanical actuator may comprise a moveable wedge.
In some examples, the mechanical actuator is rotationally driven to produce a linear force. Thus, the method according to the present disclosure may comprise driving the mechanical actuator rotationally, to produce a linear force. In one or more examples, the mechanical actuator may comprise a screw mechanism. Any suitable screw mechanism may be used, for example, comprising a cylindrical shaft with helical threads around the outside of the shaft. Optionally, the screw mechanism may comprise a worm screw, or one or more screws or bolts. Thus, the method according to the present disclosure may comprise actuating the screw mechanism, e.g. by hand or using a tool such as a crank, screwdriver or spanner. The use of a screw mechanism as the mechanical actuator provides the advantages that a screw mechanism is small and can therefore be easily accommodated adjacent to the safety actuation mechanism without interfering with the suspension member connection, and furthermore that a screw mechanism is easily actuated using standard tools.
In some examples, the mechanical actuator further comprises a pressure bar configured to contact the safety actuation mechanism in at least two positions, so as to distribute the force which is applied by the mechanical actuator to the safety actuation mechanism. Optionally, the pressure bar contacts the connection in at least two positions. This provides a particularly simple arrangement, in which the mechanical actuator is arranged to apply force to the safety actuation mechanism, but in such a way that localised wear or damage to the connection is reduced, or eliminated. In some examples, the connection may be a counterweight sheave. The pressure bar may be arranged to contact either end of the counterweight sheave. Alternatively, the connection may be an end hitch of a suspension member.
In some examples, there may be a single mechanical actuator. Alternatively, there may be more than one mechanical actuator, optionally two mechanical actuators. In some examples, the one or more mechanical actuators are located centrally on the elevator counterweight assembly.
In some examples, the safety actuation mechanism comprises at least one lever, wherein the at least one safety brake comprises a safety brake arm, and wherein the at least one lever contacts the safety brake arm, such that when the safety actuation mechanism moves between the normal position and the safety position, the at least one lever is moved, thereby moving the safety brake arm, which causes actuation of the safety brake. Optionally, the safety actuation mechanism comprises a first lever and a second lever, wherein the first and second levers are located on opposing sides of the safety actuation mechanism, wherein the elevator counterweight assembly comprises a first safety brake, comprising a first safety brake arm contacted by the first lever, and a second safety brake comprising a second safety brake arm contacted by the second lever. Optionally, the mechanical actuator is located centrally between the first lever and the second lever. This helps to apply a balanced force, thus avoiding damage caused by imbalance e.g. bending. In some examples, the connection is located centrally between the first lever and the second lever. Thus, if both the connection and the mechanical actuator are located centrally, the mechanical actuator is able to apply balanced force directly to the connection.
In some examples, the safety actuation mechanism further comprises at least one biasing spring, configured to bias the safety actuation mechanism towards the safety position. Optionally, the safety actuation mechanism comprises a first biasing spring, located at a first side of the connection, and a second biasing spring, located at a second, opposing side of the connection.
In some examples, the counterweight structure comprises at least one weight supported by a pair of uprights, wherein the safety actuation mechanism is mounted between the pair of uprights. In some examples, the counterweight structure comprises an upper crosshead, on which the mechanical actuator is mounted.
According to a further aspect of this disclosure there is provided an elevator system comprising:
In some examples, the elevator car defines an interior space for accommodating passengers and/or cargo, the elevator car comprising a working platform moveable between a stowed position, above the interior space, and an operational position, suspended within the interior space.
In some examples, the method according to the present disclosure further comprises moving an elevator car in a hoistway to be adjacent to the elevator counterweight assembly; and deploying a working platform within the elevator car, the working platform being in an operational position, allowing a person standing on the working platform to access the mechanical actuator of the elevator counterweight assembly. For example, the elevator car and elevator counterweight assembly may both be moved to a mid-rise position.
This advantageously enables a maintenance person to carry out testing and maintenance on the elevator counterweight assembly without having to enter the hoistway. Furthermore, by using the mechanical actuator of the present disclosure, the maintenance person is able to test the counterweight without having to use tools which may be heavy and cumbersome or not easily accessible e.g. a ladder or a hydraulic jack. This improves both efficiency and safety for the handover test, by avoiding pit access and allowing a maintenance person to engage the at least one safety brake for test purposes from the working platform inside the elevator car.
Certain preferred examples of this disclosure will now be described, by way of example only, and with reference to the accompanying drawings, in which:
The safety actuation mechanism 6 includes a counterweight sheave 7 and a pair of suspension members 8, arranged to contact the counterweight sheave 7 and thereby suspend the counterweight 1. The counterweight sheave 7 is attached on each side to a lever 9a, 9b, which each contact a respective safety brake arm (not seen in
It is desirable to be able to regularly test the function of the safety actuation mechanism 6 i.e. to test that downwards movement of the counterweight sheave 7 does in fact result in automatic actuation of the safety brakes 2a, 2b. An elevator counterweight assembly including a simple and safe testing mechanism according to the present disclosure is shown in
The elevator counterweight assembly 11 of
Typically these weights are such that the counterweight is heavier than the elevator car, e.g. approximately equal to the weight of the elevator car plus half of the maximum load of the elevator car. This is so that the counterweight balances the weight of the elevator car even when the elevator car is carrying passengers or other load. A safety actuation mechanism 16 is arranged below the upper crosshead 15. The safety actuation mechanism 16 includes a connection 17 suitable for connecting to one or more suspension members 18 (e.g. ropes or belts). The connection 17 in this example is a counterweight sheave, around which the suspension members 18 are passed. The safety actuation mechanism 16 further comprises at least one biasing spring 221a, 221b, configured to bias the safety actuation mechanism 16 towards the safety position. As seen in
In the event of a malfunction of the elevator system causing the suspension members 18 to lose tension and go slack, the connection 17 will no longer be lifted by tension in the suspension members 18. There is therefore no longer any force acting to compress biasing springs 221a, 221b, located on either side of the connection 17. The biasing springs 221a, 221b therefore expand, pushing the connection 17 downwards (along with gravity acting to pull the connection 17 downwards). As a result, the connection (e.g. counterweight sheave) 17 will drop i.e. move downwards, away from the upper crosshead 15 i.e. the connection (e.g. counterweight sheave) 17 will move relative to the counterweight structure 38, including relative to the safety brakes 12a, 12b, which are fixed onto the uprights 20a, 20b of the elevator counterweight assembly 11. This "downward" position of the safety actuation mechanism 16 relative to the counterweight structure 38 is referred to as the "safety position". As a result of the relative movement, the levers 19a, 19b will pivot about their respective pivot points, and will therefore move the safety brake arms 26a, 26b of the safety brakes 12a, 12b. This actuates the safety brakes 12a, 12b, causing the safety brakes, if functioning correctly, to engage with the guide rails 13a, 13b. This results in an emergency stop of the elevator counterweight assembly 11.
The elevator counterweight assembly 11 of
The mechanical actuator 22 is shown in its normal position, in which it does not apply any force to the safety actuation mechanism 16. In this position, the mechanical actuator 22 extends a first distance 30 above the upper crosshead 15. This distance may, for example, be approximately 50 mm.
As described above, in the event of an emergency which results in the counterweight suspension members 18 losing tension and going slack, the safety actuation mechanism 16 will move relative to counterweight structure 38 (i.e. the rest of the counterweight), actuating the safety brakes 12a, 12b. The mechanical actuator 22 according to the present disclosure provides a mechanism by which to create relative movement between the safety actuation mechanism 16 and the counterweight structure 38, and to therefore test that this relative movement causes the safety brakes 12a, 12b to be applied, as it should if everything is functioning properly.
For this purpose, the mechanical actuator 22 can be actuated to apply a force to the safety actuation mechanism 16, specifically to the connection 17, which in the example shown is a counterweight sheave.
As described above, in order to engage the safety brakes 12a, 12b all that is required is a relative movement between the safety actuation mechanism 16 and the safety brakes 12a, 12b mounted on the uprights 20a, 20b of the counterweight structure 38. Thus, although it may be that a slack rope during normal operation will cause the safety actuation mechanism 16 to move downwards relative to the counterweight structure 38, considered from the frame of reference of the hoistway, in the handover test procedure as described herein, it is the counterweight structure 38 (e.g. including the uprights 20a, 20b and the weights 14), which is actually moved upwards relative to the safety actuation mechanism 16, in particular relative to the connection 17 (e.g. counterweight sheave), which is held at an absolute position in the hoistway due to tension in the suspension members 18. This is represented by the position reference line 60, which is represented in
This relative movement results in the same pivoting of the levers 19a, 19b, as occurs in response to a slack rope scenario during operation of the elevator system, and therefore should result in the engaging of the safety brakes 12a, 12b. Thus, the mechanical actuator 22 can be used to test the operation of the safety actuation mechanism 16 at any given time.
It can be seen in these Figures that the mechanical actuator 22 is connected to a pressure bar 34. The pressure bar 34 is contacted by the mechanical actuator 22 and is arranged to contact the safety actuation mechanism 16 in at least two positions. In the example shown, the pressure bar 34 is arranged to contact the connection 17, which in this example is a counterweight sheave 17, at opposing ends. This pressure bar 34 distributes the force which is applied by the mechanical actuator 22 so as to avoid localised wear or damage to a particular part of the safety actuation mechanism 16, or connection 17 (e.g. counterweight sheave).
In this example the mechanical actuator 22 is a screw mechanism, shown as a bolt, that can be manually actuated by turning, e.g. the mechanical actuator 22 is rotationally driven (by hand or a suitable tool) to produce a linear force on the safety actuation mechanism 16 (via the pressure bar 34). For example, a standard M20 bolt may be used. However, it will be appreciated that other types of mechanical actuator 22 may be employed instead. For example, the mechanical actuator 22 could be a ratchet or driving wedge.
In this example the mechanical actuator 22 is located centrally between the levers 19a, 19b. The pressure bar 34 is useful for spreading the force applied by a single mechanical actuator 22. A single mechanical actuator 22 takes up little space and can be arranged between the two suspension members 18 (as seen in
In particular, if the elevator car 42 and the elevator counterweight assembly 11 are brought to midrise i.e. both to a height which is half of the total hoistway height, such that the elevator car 42 and the elevator counterweight assembly 11 are adjacent to each other and approximately at the same height, a maintenance person standing on the working platform 46 can access the elevator counterweight assembly 11 for maintenance purposes.
In particular, the maintenance person is able to access the mechanical actuator 22 described above, and therefore to test the functioning of the safety actuation mechanism 16. The steps of the method for carrying out this handover test are:
It will be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more specific examples thereof, but is not limited to these aspects; many variations and modifications are possible, within the scope of the accompanying claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.